Version 3.5.6.

src/mips/full-codegen-mips.cc

Index: src/mips/full-codegen-mips.cc
diff --git a/src/mips/full-codegen-mips.cc b/src/mips/full-codegen-mips.cc
index 4943a03a1a71922ed1f69b92b9f1b7bbd3bcb08d..d8909c9ddd4c536affd089f16c5e080986dcf8c9 100644
--- a/src/mips/full-codegen-mips.cc
+++ b/src/mips/full-codegen-mips.cc
@@ -4052,6 +4052,10 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
     __ Branch(if_true, eq, v0, Operand(at));
     __ LoadRoot(at, Heap::kFalseValueRootIndex);
     Split(eq, v0, Operand(at), if_true, if_false, fall_through);
+  } else if (FLAG_harmony_typeof &&
+             check->Equals(isolate()->heap()->null_symbol())) {
+    __ LoadRoot(at, Heap::kNullValueRootIndex);
+    Split(eq, v0, Operand(at), if_true, if_false, fall_through);
   } else if (check->Equals(isolate()->heap()->undefined_symbol())) {
     __ LoadRoot(at, Heap::kUndefinedValueRootIndex);
     __ Branch(if_true, eq, v0, Operand(at));
@@ -4069,8 +4073,10 @@ void FullCodeGenerator::EmitLiteralCompareTypeof(Expression* expr,
 
   } else if (check->Equals(isolate()->heap()->object_symbol())) {
     __ JumpIfSmi(v0, if_false);
-    __ LoadRoot(at, Heap::kNullValueRootIndex);
-    __ Branch(if_true, eq, v0, Operand(at));
+    if (!FLAG_harmony_typeof) {
+      __ LoadRoot(at, Heap::kNullValueRootIndex);
+      __ Branch(if_true, eq, v0, Operand(at));
+    }
     // Check for JS objects => true.
     __ GetObjectType(v0, v0, a1);
     __ Branch(if_false, lt, a1, Operand(FIRST_NONCALLABLE_SPEC_OBJECT_TYPE));